Structured bottom electrode for MTJ containing devices

ABSTRACT

A bottom electrode structure for a magnetic tunnel junction (MTJ) containing device is provided. The bottom electrode structure includes a mesa portion that is laterally surrounded by a recessed region. The recessed region of the bottom electrode structure is laterally adjacent to a dielectric material, and a MTJ pillar is located on the mesa portion of the bottom electrode structure. Such a configuration shields the recessed region from impinging ions thus preventing deposition of resputtered conductive metal particles from the bottom electrode onto the MTJ pillar.

BACKGROUND

The present application relates to a magnetic tunnel junction (MTJ)containing device and a method of forming the same. More particularly,the present application relates to a MTJ containing device that includesa magnetic tunnel junction (MTJ) pillar located on a mesa portion of abottom electrode structure, the mesa portion is laterally surrounded bya recessed region of the bottom electrode structure.

Magnetoresistive random access memory (MRAM) is a non-volatile randomaccess memory technology in which data is stored by magnetic storageelements. These elements are typically formed from two ferromagneticplates, each of which can hold a magnetization, separated by a thindielectric layer, i.e., the tunnel barrier. One of the two plates is apermanent magnetic set to a particular polarity; the other plate'smagnetization can be changed to match that of an external field to storememory. Such a configuration is known as a magnetic tunnel junction(MTJ) pillar.

In such MTJ containing devices, the bottom electrode that is connectedto the MTJ pillar can be a source of resputtered conductive metalparticles that can deposit on a sidewall of the MTJ pillar, especiallywhen an ion beam etching (IBE) process is used to clean the sidewall ofthe MTJ pillar. If resputtered conductive metal particles deposit on thetunnel barrier material of the MTJ pillar, electrical shorts may arise,which is a common failure mode. This problem is particularly apparentwhen the critical dimension (CD) of the bottom electrode exceeds that ofthe MTJ pillar, which is not an unlikely occurrence due to thedifficulty in maintaining circularity at small CDs for hole features.

There is thus a need for a method that can prevent the deposition ofsuch resputtered conductive metal particles from the bottom electrode onthe sidewall of the MTJ pillar.

SUMMARY

A bottom electrode structure for a magnetic tunnel junction (MTJ)containing device is provided. The bottom electrode structure includes amesa portion that is laterally surrounded by a recessed region. Therecessed region of the bottom electrode structure is laterally adjacentto a dielectric material, and a MTJ pillar is located on the mesaportion of the bottom electrode structure. Such a configuration shieldsthe recessed region from impinging ions thus preventing deposition ofresputtered conductive metal particles from the bottom electrode ontothe MTJ pillar. Secondly, as the predominantly exposed surface of thebottom electrode structure in the recessed region is now nearly verticalrather than horizontal, the angle of resputtering changes such thatdeposition of resputtered conductive metal particles becomes lesslikely.

In one aspect of the present application, a magnetic tunnel junction(MTJ) containing device such as, for example, a memory device or asensor is provided. In one embodiment, the MTJ containing deviceincludes a MTJ pillar located on a mesa portion of a bottom electrodestructure, wherein the mesa portion is laterally surrounded by arecessed region of the bottom electrode structure. By “laterallysurrounded” it is meant that the recessed region is located on theperimeter of the mesa portion. A dielectric material is locatedlaterally adjacent to the recessed region, and a top electrode islocated on the MTJ pillar.

In another aspect of the present application, a method of forming amagnetic tunnel junction (MTJ) containing device is provided. In oneembodiment, the method includes forming a structure including adielectric material located adjacent to a bottom electrode having anentirely planar topmost surface, a multilayered magnetic tunnel junction(MTJ) stack located on a portion of the entirely planar topmost surfaceof the bottom electrode and a top electrode located on the multilayeredMTJ stack. The multilayered MTJ stack is then etched to provide a MTJpillar. Next, a passivation material spacer is formed on sidewalls ofeach of the top electrode and the MTJ pillar. The physically exposedportion of the bottom electrode is then recessed to provide a bottomelectrode structure containing a mesa portion and a recessed regionlaterally surrounding the mesa portion. In some embodiments, adielectric material layer is formed to fill in the recessed region ofthe bottom electrode structure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross sectional view of an exemplary MTJ containing deviceof the present application and during an early stage of fabrication, theMTJ containing device including a dielectric material located adjacentto a bottom electrode having an entirely planar topmost surface, amultilayered magnetic tunnel junction (MTJ) stack located on a portionof the entirely planar topmost surface of the bottom electrode and a topelectrode located on the multilayered MTJ stack.

FIG. 2 is a cross sectional view of the exemplary MTJ containing deviceof FIG. 1 after etching the multilayered MTJ stack to provide a MTJpillar.

FIG. 3 is a cross sectional view of the exemplary MTJ containing deviceof FIG. 2 after forming a passivation material layer on the physicallyexposed surfaces of the top electrode and the MTJ pillar.

FIG. 4 is a cross sectional view of the exemplary MTJ containing deviceof FIG. 3 after etching the passivation material layer to provide apassivation material spacer on a sidewall of each of the top electrodeand the MTJ pillar.

FIG. 5 is a cross sectional view of the exemplary MTJ containing deviceof FIG. 4 after recessing a physically exposed portion of the bottomelectrode to provide a bottom electrode structure containing a mesaportion and a recessed region laterally surrounding the mesa portion.

FIG. 6 is a cross sectional view of the exemplary MTJ containing deviceof FIG. 5 after forming a dielectric material layer to fill in therecessed region of the bottom electrode structure.

DETAILED DESCRIPTION

The present application will now be described in greater detail byreferring to the following discussion and drawings that accompany thepresent application. It is noted that the drawings of the presentapplication are provided for illustrative purposes only and, as such,the drawings are not drawn to scale. It is also noted that like andcorresponding elements are referred to by like reference numerals.

In the following description, numerous specific details are set forth,such as particular structures, components, materials, dimensions,processing steps and techniques, in order to provide an understanding ofthe various embodiments of the present application. However, it will beappreciated by one of ordinary skill in the art that the variousembodiments of the present application may be practiced without thesespecific details. In other instances, well-known structures orprocessing steps have not been described in detail in order to avoidobscuring the present application.

It will be understood that when an element as a layer, region orsubstrate is referred to as being “on” or “over” another element, it canbe directly on the other element or intervening elements may also bepresent. In contrast, when an element is referred to as being “directlyon” or “directly over” another element, there are no interveningelements present. It will also be understood that when an element isreferred to as being “beneath” or “under” another element, it can bedirectly beneath or under the other element, or intervening elements maybe present. In contrast, when an element is referred to as being“directly beneath” or “directly under” another element, there are nointervening elements present.

Referring now to FIG. 1, there is illustrated an exemplary magnetictunnel junction (MTJ) containing device of the present application andduring an early stage of fabrication. Exemplary MTJ containing devicesinclude, but are not limited to, memory devices (e.g., MRAM orspin-transfer torque (STT) MRAM), or sensors such as, for example,pressure sensors. Notably, the exemplary MTJ containing device shown inFIG. 1 includes a dielectric material located adjacent to a bottomelectrode 14 having an entirely planar topmost surface, a multilayeredmagnetic tunnel junction (MTJ) stack 18 located on a portion of theentirely planar topmost surface of the bottom electrode 14 and a topelectrode 26 located on the multilayered MTJ stack 18.

It is noted that the drawings of the present application illustrate adevice area in which a MTJ containing device will be formed. A non-MTJcontaining device area may be located adjacent to the MTJ containingdevice area illustrated in the drawings of the present application. Itis also noted that while a single bottom electrode 14 and a single topelectrode 26 are described and illustrated, the present application canbe used when a plurality of bottom electrodes 14 and a plurality of topelectrodes 26 are formed.

As is shown, the bottom electrode 14 is located on a surface of anelectrically conductive structure 12 that is embedded in an interconnectdielectric material layer 10. Although not shown, a diffusion barrierliner can be formed on the sidewalls and bottom wall of the electricallyconductive structure 12. Collectively, the electrically conductivestructure 12, the diffusion barrier liner (if present), and theinterconnect dielectric material layer 10 provide an interconnect level.It is noted that at least one other interconnect level and/or amiddle-of-the-line (MOL) level may be located beneath the interconnectlevel including the interconnect dielectric material layer 10, theelectrically conductive structure 12, and, if present, the diffusionbarrier liner. These other levels are not shown for clarity.

In the illustrated embodiment, the dielectric material that is locatedadjacent to the bottom electrode 14 is a dielectric capping materialprovided by dielectric capping layer 13. In another embodiment (notillustrated, but which can be derived readily from FIG. 1), thedielectric material that is located adjacent to the bottom electrode 14,is an upper portion of an interconnect dielectric material of aninterconnect dielectric material layer 10. In such an embodiment, thedielectric capping layer 13 is omitted and the interconnect dielectricmaterial layer 10 extends above electrically conductive structure 12that is embedded in the interconnect dielectric material layer 10 suchthat the extended portion of the interconnect dielectric material layer10 is located laterally adjacent to the bottom electrode 14. In eitherembodiment, the bottom electrode 14 has an entirely planar topmostsurface that is coplanar with a topmost surface of the dielectricmaterial that is located adjacent to the bottom electrode 14.

The interconnect dielectric material layer 10 can be composed of anyinterconnect dielectric material including, for example, silicondioxide, silsesquioxanes, C doped oxides (i.e., organosilicates) thatincludes atoms of Si, C, O and H, thermosetting polyarylene ethers, ormultilayers thereof. The term “polyarylene” is used in this applicationto denote aryl moieties or inertly substituted aryl moieties which arelinked together by bonds, fused rings, or inert linking groups such as,for example, oxygen, sulfur, sulfone, sulfoxide, carbonyl and the like.

The electrically conductive structure 12 is composed of an electricallyconductive metal or metal alloy. Examples of electrically conductivematerials that may be used in the present application include copper(Cu), aluminum (Al), or tungsten (W), while an example of anelectrically conductive metal alloy is a Cu—Al alloy.

In some embodiments, a diffusion barrier liner is formed along thesidewalls and a bottom wall of the electrically conductive structure 12.In some embodiments, no diffusion barrier liner is present. Thediffusion barrier liner is composed of a diffusion barrier material(i.e., a material that serves as a barrier to prevent a conductivematerial such as copper from diffusing there through). Examples ofdiffusion barrier materials that can be used in providing the diffusionbarrier liner include, but are not limited to, Ta, TaN, Ti, TiN, Ru,RuN, RuTa, RuTaN, W, or WN. In some embodiments, the diffusion barriermaterial may include a material stack of diffusion barrier materials. Inone example, the diffusion barrier material may be composed of a stackof Ta/TaN.

The interconnect level including the interconnect dielectric materiallayer 10, the electrically conductive structure 12, and, if present, thediffusion barrier liner may be formed utilizing conventional processesthat are well-known to those skilled in the art including, for example,a damascene process. So as not to obscure the method of the presentapplication, the techniques used to form the interconnect levelincluding the interconnect dielectric material layer 10, theelectrically conductive structure 12, and, if present, the diffusionbarrier liner are not provided herein.

In some embodiments (not shown), the bottom electrode 14 is located on arecessed surface of the electrically conductive structure 12. In such anembodiment, and prior to forming the bottom electrode 14, an upperportion of the electrically conductive structure 12 is removed utilizinga recess etching process, and thereafter the bottom electrode 14 isformed upon the recessed surface of the electrically conductivestructure 12. In such an embodiment, the bottom electrode 14 would belocated on an entirety of the recessed topmost surface of theelectrically conductive structure 12. Also, and in such an embodiment,the bottom electrode 14 would have a topmost surface that is coplanarwith a topmost surface of the interconnect dielectric material layer 10,and an upper portion of the interconnect dielectric material layer 10would be laterally adjacent to each sidewall of the bottom electrode 14.Further, and in such an embodiment, dielectric capping layer 13 shown inFIG. 1 can be omitted from the structure.

In other embodiments and as illustrated in FIG. 1, the bottom electrode14 is formed on a non-recessed surface of the electrically conductivestructure 12. In such an embodiment, a dielectric capping layer 13 islocated laterally adjacent to the bottom electrode 14 and on a surfaceof the interconnect dielectric material layer 10. In this embodiment, asmaller width bottom electrode 14 can be provided that does not coverthe entirety of the topmost surface of the electrically conductivestructure 12.

When present, the dielectric capping layer 13 may be composed of anydielectric material such as, for example, SiC, Si₃N₄, SiO₂, a carbondoped oxide, a nitrogen and hydrogen doped silicon carbide SiC(N,H) ormultilayers thereof. The dielectric capping layer 13 can be formedutilizing a conventional deposition process such as, for example,chemical vapor deposition (CVD), plasma enhanced chemical vapordeposition (PECVD), chemical solution deposition, evaporation, or plasmaenhanced atomic layer deposition (PEALD). In some embodiments, and asexplained above, the dielectric capping layer 13 may be omitted from theexemplary MTJ containing device. In some embodiments and as isillustrated in FIG. 1, the bottom electrode 14 has a topmost surfacethat is coplanar with a topmost surface of a dielectric capping layer 13that may be present laterally adjacent to the bottom electrode 14 and ona topmost surface of the interconnect dielectric material layer 10.

The dielectric capping layer 13 may be formed prior to, or after,forming the bottom electrode 14. In embodiments when the dielectriccapping layer 13 is formed prior to the bottom electrode 14, a blanketlayer of dielectric capping material is formed and thereafter an openingis formed (by photolithography and etching) in the dielectric cappingmaterial. The bottom electrode 14, as defined below, is then formed inthe opening. In such an embodiment, the bottom electrode 14 is formed bydeposition, followed by a planarization process. In embodiments in whichthe bottom electrode 14 is formed prior to the dielectric capping layer13, the bottom electrode is formed by deposition and patterning, andthereafter the dielectric capping material is deposited and a subsequentplanarization process may be performed.

Bottom electrode 14, which is present on a surface of the electricallyconductive structure 12, may be composed of a conductive material suchas, for example, Ta, TaN, Ti, TiN, Ru, RuN, RuTa, RuTaN, Co, CoWP, CoN,W, WN or any combination thereof. The bottom electrode 14 may have athickness from 2 nm to 25 nm; other thicknesses are possible and can beused in the present application as the thickness of the bottom electrode14. The bottom electrode 14 may be formed by a deposition process suchas, for example, sputtering, atomic layer deposition (ALD), chemicalvapor deposition (CVD), plasma enhanced chemical vapor deposition(PECVD) or physical vapor deposition (PVD). An etch back process, aplanarization process (such as, for example, chemical mechanicalpolishing), or a patterning process (such as, for example, lithographyand etching) may follow the deposition of the conductive material thatprovides the bottom electrode 14.

The MTJ stack 18 includes at least a magnetic reference layer 20, atunnel barrier layer 22, and a magnetic free layer 24 as configured inFIG. 1. Other MTJ stack 18 configurations are possible such as, forexample, the magnetic free layer 24 being located at the bottom of theMTJ stack 18 and the magnetic reference layer 20 being at the top of theMTJ stack 18. In some embodiments (not shown), the MTJ stack 18 may alsoinclude a non-magnetic spacer layer located on the magnetic free layer,a second magnetic free layer located on the non-magnetic spacer layer,and/or a MTJ cap layer located on the magnetic free layer 24 or on thesecond magnetic free layer. The various material layers of the MTJ stack18 can be formed by utilizing one or more deposition processes such as,for example, plating, sputtering, plasma enhanced atomic layerdeposition (PEALD), plasma enhanced chemical vapor deposition (PECVD) orphysical vapor deposition (PVD).

The magnetic reference layer 20 has a fixed magnetization. The magneticreference layer 20 may be composed of a metal or metal alloy (or a stackthereof) that includes one or more metals exhibiting high spinpolarization. In alternative embodiments, exemplary metals for theformation of the magnetic reference layer 20 include iron, nickel,cobalt, chromium, boron, or manganese. Exemplary metal alloys mayinclude the metals exemplified by the above. In another embodiment, themagnetic reference layer 20 may be a multilayer arrangement having (1) ahigh spin polarization region formed from of a metal and/or metal alloyusing the metals mentioned above, and (2) a region constructed of amaterial or materials that exhibit strong perpendicular magneticanisotropy (strong PMA). Exemplary materials with strong PMA that may beused include a metal such as cobalt, nickel, platinum, palladium,iridium, or ruthenium, and may be arranged as alternating layers. Thestrong PMA region may also include alloys that exhibit strong PMA, withexemplary alloys including cobalt-iron-terbium, cobalt-iron-gadolinium,cobalt-chromium-platinum, cobalt-platinum, cobalt-palladium,iron-platinum, and/or iron-palladium. The alloys may be arranged asalternating layers. In one embodiment, combinations of these materialsand regions may also be employed.

The tunnel barrier layer 22 is composed of an insulator material and isformed at such a thickness as to provide an appropriate tunnelingresistance. Exemplary materials for the tunnel barrier layer 22 includemagnesium oxide, aluminum oxide, and titanium oxide, or materials ofhigher electrical tunnel conductance, such as semiconductors orlow-bandgap insulators.

The magnetic free layer 24 may be composed of a magnetic material (or astack of magnetic materials) with a magnetization that can be changed inorientation relative to the magnetization orientation of the magneticreference layer 20. Exemplary magnetic materials for the magnetic freelayer 24 include alloys and/or multilayers of cobalt, iron, alloys ofcobalt-iron, nickel, alloys of nickel-iron, and alloys ofcobalt-iron-boron.

If present, the non-magnetic metallic spacer layer is composed of anon-magnetic metal or metal alloy that allows magnetic information to betransferred therethrough and also permits the two magnetic free layersto couple together magnetically, so that in equilibrium the first andsecond magnetic free layers are always parallel. The non-magneticmetallic spacer layer allows for spin torque switching between the firstand second magnetic free layers.

If present, the second magnetic free layer may include one of themagnetic materials mentioned above for magnetic free layer 24. In oneembodiment, the second magnetic free layer is composed of a samemagnetic material as the magnetic free layer 24. In another embodiment,the second magnetic free layer is composed of a magnetic material thatis compositionally different from the magnetic free layer 24.

If present, the MTJ cap layer can be composed of Nb, NbN, W, WN, Ta,TaN, Ti, TiN, Ru, Mo, Cr, V, Pd, Pt, Rh, Sc, Al or other high meltingpoint metals or conductive metal nitrides. The MTJ cap layer may have athickness from 2 nm to 25 nm; other thicknesses are possible and can beused in the present application as the thickness of the MTJ cap layer.

The top electrode 26 may be composed of one of the conductive materialsmentioned above for the bottom electrode 14. In one embodiment, theconductive material that provides the top electrode 26 iscompositionally different from the bottom electrode 14. In anotherembodiment, the conductive material that provides the top electrode 26is compositionally the same as the bottom electrode 14. In such anembodiment, a surface treatment process can be performed on the topelectrode 26 to increase the top electrode's etch resistance, before thebottom electrode 14 is physically exposed. The conductive material thatprovides the top electrode 26 is typically compositionally differentfrom the optional MTJ cap layer. The top electrode 26 can have athickness within the thickness range mentioned above for the bottomelectrode 14. The top electrode 26 may be formed utilizing one of thedeposition processes mentioned above in providing the bottom electrode14, followed by performing a patterning process, such as, for example,photolithography and etching.

Referring now to FIG. 2, there is illustrated the exemplary MTJcontaining device of FIG. 1 after etching the multilayered MTJ stack 18to provide a MTJ pillar 18P. The top electrode 26 is used as an etchmask during this step of the present application. The etching of themultilayered MTJ stack 18 comprises one or more etching processes. Theone or more etching processed may include one or more reactive ionetching processes. The MTJ pillar 18P and the top electrode 26 aretypically cylindrical in shape. However, other asymmetric shapes arepossible and can be utilized in the present application.

The MTJ pillar 18P has a sidewall that is vertically aligned to thesidewall of the top electrode 26. The MTJ pillar 18P includes at least aremaining portion of the magnetic reference layer 20 (hereinaftermagnetic reference material 20P), a remaining portion of the tunnelbarrier layer 22 (hereinafter tunnel barrier material 22P) and aremaining portion of the magnetic free layer 24 (hereinafter magneticfree material 24P). In some embodiments, the MTJ pillar 18P may alsoinclude a remaining portion of the non-magnetic spacer, a remainingportion of the second magnetic reference layer, and/or a remainingportion of the MTJ cap layer.

As is shown in the drawing, this etch physically exposes a portion ofthe entirely planar topmost surface of the bottom electrode 14. Thephysically exposed portion of the entirely planar topmost surface of thebottom electrode 14 can be a source of conductive materials which duringan angled IBE process used to clean the sidewall of the MTJ pillar 18Pcan be resputtered and deposited as conductive metal particles on thesidewall of the MTJ pillar 18P. As mentioned above, such resputteredconductive metal particles that deposit on the sidewall of the MTJpillar causes electrical shorts. Thus, and in the present application,such an angled IBE is not performed at this stage of the presentapplication.

Referring now to FIG. 3, there is illustrated the exemplary MTJcontaining device of FIG. 2 after forming a passivation material layer28L on the physically exposed surfaces of the top electrode 26 and theMTJ pillar 18P. The passivation material layer 28L also extends onto thephysically exposed surface of either the dielectric capping layer 13 orthe interconnect dielectric material layer 10.

The passivation material layer 28L is composed of a dielectric material.In one example, the passivation material layer 28L is composed ofsilicon nitride. In another example, the passivation material layer 28Lmay be composed of a dielectric material that contains atoms of silicon,carbon and hydrogen. In some embodiments, and in addition to atoms ofcarbon and hydrogen, the dielectric material may include atoms of atleast one of nitrogen and oxygen. In other embodiments, and in additionto atoms of silicon, nitrogen, carbon and hydrogen, the dielectricmaterial may include atoms of boron. In one example, the passivationmaterial layer 28L may be composed of an nBLOK dielectric material thatcontains atoms of silicon, carbon, hydrogen, nitrogen and oxygen. Inalternative example, the passivation material layer 28L may be composedof a SiBCN dielectric material that contains atoms of silicon, boron,carbon, hydrogen, and nitrogen.

The passivation material layer 28L can be formed utilizing a depositionprocess such as, for example, PECVD, PVD, or PEALD. The passivationmaterial layer 28L may have a thickness from 10 nm to 200 nm. Otherthicknesses are possible and can be employed as the thickness of thepassivation material layer 28L. In some embodiments, the passivationmaterial layer 28L has a conformal thickness. The term “conformal”denotes that a material layer has a vertical thickness along horizontalsurfaces that is substantially the same (i.e., within ±5%) as thelateral thickness along vertical surfaces.

Referring now to FIG. 4, there is illustrated the exemplary MTJcontaining device of FIG. 3 after etching the passivation material layer28L to provide a passivation material spacer 28 on a sidewall of each ofthe top electrode 26 and the MTJ pillar 18P. As is shown, a bottommostsurface of the passivation material spacer 28 is located on a portion ofthe entirely planar topmost surface of the bottom electrode 14. Theetching of the passivation material layer 28L may be performed utilizingany spacer etching process such as, for example, reactive ion etching,that is selective for removing passivation material.

Referring now to FIG. 5, there is illustrated the exemplary MTJcontaining device of FIG. 4 after recessing a physically exposed portionof the bottom electrode 14 to provide a bottom electrode structure 14Scontaining a mesa portion 14M and a recessed region 15 laterallysurrounding the mesa portion 14M. The mesa portion 14M has an entirelyplanar topmost surface which is coplanar with a topmost surface of thedielectric material that is located laterally adjacent to the recessedregion 15. The recessed region 15 of the bottom electrode structure 14Shas a concave surface as shown in FIG. 5. The concave surface of therecessed region is beneath the topmost surface of the mesa portion 14Mas well as the topmost surface dielectric material that is locatedadjacent to bottom electrode structure 14S. The outermost sidewall ofthe mesa portion 14M is spaced apart from an innermost sidewall of thedielectric material that is adjacent to the recessed region 15 by adistance of 10 nm to 20 nm.

The recessing of the physically exposed portion of the bottom electrode14 utilizes the passivation material spacer 28 and the top electrode 26as a combined etch mask. The recessing may be performed utilizing a wetetching process or a dry etching process that selectively removes theconductive material of the bottom electrode 14 while minimally erodingboth the aforementioned combined etch mask (passivation material spacer28 and top electrode 26) and the physically exposed dielectric cappinglayer 13 or the interconnect dielectric material layer 10, if thedielectric capping layer 13 is not present. In one example, therecessing of the physically exposed portions of the bottom electrode 14may be performed by an HBr/O₂ or Cl₂/O₂ based plasma etch, or a wetsolution containing ammonium hydroxide, hydrogen peroxide and deionizedwater.

The recessed region 15 of the bottom electrode structure 14S has acritical dimension that exceeds that of the MTJ pillar 18P. The term“critical dimension” is used throughout the present application todenote the diameter of the feature. In one embodiment of the presentapplication, the recessed region 15 of the bottom electrode structure14S has a critical dimension from 40 nm to 80 nm, while the MTJ pillar18P has a critical dimension from 20 nm to 50 nm.

FIG. 5 illustrates a MTJ containing device of the present applicationthat includes a MTJ pillar 18P located on a mesa portion 14M of a bottomelectrode structure 14S, wherein the mesa portion 14M is laterallysurrounded by a recessed region 15 of the bottom electrode structure14S. The mesa portion 14M has an entirely planar topmost surface. Adielectric material (either dielectric capping layer 13 or an upperportion of the interconnect dielectric material layer 10) is locatedlaterally adjacent to the recessed region 15. A top electrode 26 islocated on the MTJ pillar 18P.

At this point of the present, an angled IBE process can now beperformed. Unlike the prior art, and due to the geometry of the MTJcontaining device of the present application, substantially noconductive metal particles that may be resputtered from the bottomelectrode structure 14S deposit on the sidewall of the MTJ pillar 18Pthus reducing the possibility of electrical shorts caused by theredeposit conductive metal particles. Notably, the configuration of theMTJ containing device of the present application shields the recessedregion 15 of the bottom electrode structure 14S from impinging ions thuspreventing deposition of resputtered conductive metal particles from thebottom electrode structure 14S onto the MTJ pillar 18P. Thus, and in thepresent application, improved device performance, in terms of areduction in failure mode, can be obtained.

Although not shown, another electrically conductive structure is formedcontacting a surface of the top electrode 26. This other electricallyconductive structure is embedded in another interconnect dielectricmaterial that is formed laterally adjacent to, and above, the stackincluding, the MTJ pillar 18P, and the top electrode 26.

Referring now to FIG. 6, there is illustrated the exemplary MTJcontaining device of FIG. 5 after forming a dielectric material layer30L to fill in the recessed region 15 of the bottom electrode structure14S. The dielectric material layer 30L may be composed of any dielectricmaterial such as one of the dielectric materials mentioned above for thepassivation dielectric material layer 28L. In one embodiment, thedielectric material layer 30L is composed of a compositionally samedielectric material as the passivation material layer 28L. In anotherembodiment, the dielectric material layer 30L is composed of acompositionally different dielectric material than the passivationmaterial layer 28L. The dielectric material layer 30L may be formedutilizing any divot fill process that may include deposition and, anoptional, recess etch.

The dielectric material layer 30L of the exemplary MTJ containing deviceshown in FIG. 6 completely shields the recessed region 15 of the bottomelectrode structure 14S thus completely eliminating the likelihood ofdepositing resputtered conductive metal particles from the bottomelectrode structure 14S onto the sidewall of the MTJ pillar 18P.

Although not shown, another electrically conductive structure is formedcontacting a surface of the top electrode 26. This other electricallyconductive structure is embedded in another interconnect dielectricmaterial that is formed laterally adjacent to, and above, the stackincluding, the MTJ pillar 18P, and the top electrode 26.

While the present application has been particularly shown and describedwith respect to preferred embodiments thereof, it will be understood bythose skilled in the art that the foregoing and other changes in formsand details may be made without departing from the spirit and scope ofthe present application. It is therefore intended that the presentapplication not be limited to the exact forms and details described andillustrated, but fall within the scope of the appended claims.

What is claimed is:
 1. A magnetic tunnel junction (MTJ) containingdevice comprising: a bottom electrode structure comprising a mesaportion and a laterally adjacent recessed region; a dielectric materiallocated laterally adjacent to the recessed region of the bottomelectrode structure; a MTJ pillar located on a topmost surface of themesa portion of the bottom electrode structure; a top electrode locatedon the MTJ pillar; and a passivation material spacer located on asidewall of each of the top electrode and the MTJ pillar, wherein abottommost surface of the passivation material spacer is in directphysical contact with the topmost surface of the mesa portion of thebottom electrode structure.
 2. The MTJ containing device of claim 1,wherein the topmost surface of the mesa region of the bottom electrodestructure is coplanar with a topmost surface of the dielectric materialthat is located laterally adjacent to the recessed region.
 3. The MTJcontaining device of claim 1, wherein the bottom electrode structure islocated on a surface of an electrically conductive structure.
 4. The MTJcontaining device of claim 3, wherein the electrically conductivestructure is embedded in an interconnect dielectric material layer, andwherein an upper portion of the interconnect dielectric material layerprovides the dielectric material that is located laterally adjacent tothe recessed region.
 5. The MTJ containing device of claim 1, whereinthe dielectric material layer that is located laterally adjacent to therecessed region is a dielectric capping material layer.
 6. The MTJcontaining device of claim 1, wherein the recessed region of the bottomelectrode structure has a concave surface.
 7. The MTJ containing deviceof claim 1, wherein the MTJ pillar comprises a magnetic referencematerial, a tunnel barrier material, and a magnetic free material,wherein the magnetic reference material forms an interface with the mesaportion of the bottom electrode structure.
 8. The MTJ containing deviceof claim 1, wherein the recessed region has a critical dimension thatexceeds that of the MTJ pillar.
 9. The MTJ containing device of claim 1,wherein no resputtered conductive metal particles are present on asidewall of the MTJ pillar.
 10. The MTJ containing device of claim 1,further comprising a dielectric material layer located on the dielectricmaterial and present in, and completely filling, the recessed region ofthe bottom electrode structure, wherein a sidewall of the dielectricmaterial layer directly contacts only a lower portion of the passivationmaterial spacer.
 11. A magnetic tunnel junction (MTJ) containing devicecomprising: a bottom electrode structure comprising a mesa portion and alaterally adjacent recessed region; a dielectric material locatedlaterally adjacent to the recessed region of the bottom electrodestructure; a MTJ pillar located on a topmost surface of the mesa portionof the bottom electrode structure; a top electrode located on the MTJpillar; and a dielectric material layer located on the dielectricmaterial and present in, and completely filling, the recessed region ofthe bottom electrode structure, wherein the dielectric material layerhas a height that is less than a height of the MTJ pillar.